


Birthday Surprise

by eeyore9990



Category: Teen Wolf (TV)
Genre: Biting, Blow Jobs, Cunnilingus, F/M, First Time, Knotting, Loss of Virginity, M/M, Multi, Other, PWP, Reverse Knotting, Sibling Incest, Spanking, There's a lot going on in this fic, Threesome, female knotting, uhhh...lions and tigers and bears oh my?
Language: English
Status: Completed
Published: 2014-04-18
Updated: 2014-04-18
Packaged: 2018-01-19 20:54:18
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 5,735
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/1483564
Author URL: https://archiveofourown.org/users/eeyore9990/pseuds/eeyore9990
Summary: <blockquote class="userstuff">
              <p>Derek and Cora show up on Stiles' birthday to pick him up and <i>take him</i> for his birthday surprise.  The only hint Derek will give Stiles when he asks is that it involves eating out.</p><p>(The bad puns are strong with these two.)</p>
            </blockquote>





	Birthday Surprise

**Author's Note:**

  * For [badwolfbadwolf](https://archiveofourown.org/users/badwolfbadwolf/gifts).



> There's no explanation given for the relationship between Derek and Cora. If it makes you feel better, you can imagine that they worked this arrangement out because they both want Stiles and their mother taught them to share.
> 
> I personally just like the idea that they don't give a fuck.
> 
> Happy birthday to Stiles (who apparently just turned 18 according to some version of the canon time-line (ahahahahahaha) and also to my lovely badwolfbadwolf. You know this is gonna be the best decade ever, because you get to spend it knowing ME. Helllllll yeah!

Stiles stops trying to wrestle open the driver's side door on the Jeep when a black SUV pulls up inches from his bumper, preventing him from being able to go anywhere even if he did get in. It's a classic hunter's move, so he's extra suspicious. He fists his keys in his hand, sharp edges out between his knuckles, and doesn't relax until the passenger side window rolls smoothly down to show Cora staring back at him, Derek just visible behind her in the driver's seat. 

She shoots a vaguely amused glance at his fist, then jerks her head. "Get in, loser."

"You know, that stopped being funny in 2004."

"What a coincidence! So did you. Now, are you going to get in so we can take you for your birthday surprise or what?" She's got on dark sunglasses that shield almost the entire upper half of her face, but he can still see her eyebrows judging him and from long experience Stiles knows that means she's giving him a baleful look.

"Keep your panties on, Hale," he says, trying to look casual and not like his heart just tripped over itself at the very idea of them knowing that it's his birthday. And okay, maybe he's mentioned it a lot—a lot, a lot—when he's around the pack, but he's still kinda floored that Cora and maybe even Derek paid enough attention to his exuberant rambling to take note of the day. 

He opens the back door of the SUV and throws his backpack inside before crawling into the back seat. He doesn't have a chance to shut the door before Derek, who's driving, peels out fast enough that the momentum slams the door shut for him. 

"Whose panties?" Derek asks, meeting his eyes in the rear view mirror. 

Stiles blinks because that sounded like flirty innuendo. Maybe it's a new kind of death threat? "Uhh, hah," he says, stalling for time before deciding to change the subject. Scooting forward until his butt is barely in the seat, he shoulders between Cora and Derek. "You know, if you really wanted to make it a surprise, you shouldn't have said anything."

Derek snorts, braking and turning left so smoothly that Stiles barely shifts. "You act like we've never met you. Besides, it doesn't matter that you know we've planned a surprise; it's the mystery of the surprise itself that's going to bug you until you figure it out."

Some odd emotion fills Stiles—he thinks it might be some combination of awe, respect, and horror—as he breathes, "Wow. That's fucking evil." He chews on his lower lip, studying their blank-ass profiles in turn before he gives up with a loud exhale. "At least give me a hint!"

"It involves eating out."

\--

"I'm not putting my dick in your ass until she comes on your tongue." 

It's Derek's voice in his ear, his breath on Stiles' neck sending goosebumps all up and down his body, his large hand resting hot and a little heavy on Stiles' bare ass. It's his finger dragging slow and purposeful up the crack of Stiles' ass, catching on Stiles' rim to press and tug before dropping to trace lightly over the seam of his balls and start the whole journey again. 

But those are Cora's hands in his hair, her taste on his lips, and her scent filling the air. Those are her long legs parted for him, her hips jerking impatiently under him. 

Stiles would wonder how he went from being barely a blip on the Hale family radar to this, but he's not one to look a gift horse in the mouth.

"Give me your fucking _tongue_ , Stilinski," Cora growls, tugging on his head and rolling her hips. 

There's a _tsk_ ing sound next to his ear before Derek's hand disappears—Stiles is pretty sure he whimpers at the loss. But suddenly it's back with a hard slap that jolts Stiles forward, pushing his nose deep into Cora's curls. The pain takes a second to hit, but when it does, his whole ass feels like it's on fire. Sensation zings up and down his spine from the point of impact, and Stiles loses his breath at the feeling of Derek smoothly massaging the skin.

Groaning, he takes the hint and begins to tentatively lick along the folds of Cora's cunt, trying to recall the things he's read about pleasuring women. Porn vids are useless because it's not like you could ever see anything other than the back of someone's head wriggling. He vaguely recalls something about writing the alphabet on a girl's clit, but he's pretty sure he hasn't found that yet. He slides his mouth around a little, trying to get a feel for it, rolling her flavor around on his tongue and trying to figure out how to best describe the taste. He's so focused on Cora, on pleasuring her and figuring this whole cunnilingus thing out that he stops paying attention to what Derek's doing.

Which is probably why it catches him so off guard when Derek's hand swats his other ass cheek. Lifting his head, Stiles turns to glare at Derek, only to have Cora nearly twist his ears off his skull. Yelping, he faces forward again; then, before either of them can do any more damage, hurries to say, "Stop spanking me. I'm doing it!"

Derek's fingers drag over the places he's smacked, his voice sounding huskier than normal when he says, "Birthday swats are a time-honored tradition. You wouldn't want us to ignore tradition, would you? Besides," he adds, trailing one hand between Stiles' thighs and cupping him, "it doesn't really feel like you mind all that much." Giving Stiles' dick a squeeze, Derek smacks his ass again and...yeah. 

Yeah, okay, so maybe Stiles can see the allure. Because his ass feels a bit like it's swollen and on fire, but Derek's _hand_ is squeezing Stiles' _dick_ , and his fingers are playing with the head of it, rolling around in Stiles' precome. The sensation of itchy, spreading pain from his ass and the gut-clenching pleasure from his dick meet in the middle and coalesce into a steady thrum of sensation and it's...

It's too much to think about when Cora's spread out below him, her hips twitching in his hands and her fingers digging into his scalp as she tries to get him back on task. 

He's been warned not to use his hands until given permission—from who, he's not quite sure—so he just flexes his fingers on her ass and leans back in, sucking open-mouthed kisses here and there until she lets out a low, thrilling sound. Having found his target, he focuses on it, sucking some more until he feels it, feels the hardened bit of flesh with the tip of his tongue.

Derek slaps his ass again and again, in quick, ringing succession, and Stiles is fucking gone. The only reason he hasn't come already—because, let's face it, this is pretty much every fantasy he's ever had rolled up into one giant birthday present of bliss—is because Derek did something with his balls that made him let out a muffled shriek and stopped his orgasm in its tracks. Fuck, it kinda hurt, but also kinda felt wild and hair-raising. 

So, you know, perfect metaphor for every damn thing about these particular Hales.

Trying to get his mind off his throbbing ass and strangled balls for a minute, Stiles concentrates on focusing his tongue and attention on Cora's clit. He rubs his tongue over it again and again, licking and prodding at it, just trying to feel it out, see what makes her gasp, what makes her squirm. He's still unsure, so he tries the alphabet trick, but he fucks up on 'f' and then just doodles his name with the tip of his tongue over and over. Cursive, block style, and lowercase. His tongue is all kinds of dexterous.

Derek is squeezing his ass cheeks with both hands, gripping them tight, pulling them apart for a long second, pushing them back together again. And in between every second or third rotation of this, there's another spine-tingling pop of his palm. "Seventeen," he finally says, and Stiles screws his eyes shut, pursing his lips around Cora's clit to hopefully hold back the scream he just knows is about to get spanked out of him.

But Derek's back playing with his ass: squeeze, pull, push; squeeze pull push; squeeze _pull_ push. His cheeks are spread wide when he feels Derek shift behind him and suddenly there's the meaty smack of _something_ against his hole, and Stiles has to stop licking Cora long enough to turn his head. 

"Did you just dick slap my asshole?" He's about to make a sarcastic remark when Derek spits on his ass and _rubs_ the head of his dick right there, as if to soothe the nonexistent ache. Stiles loses his breath then and cants his hips backward automatically, _feeling_ the needy grasping of his hole. Like it's greedy for Derek's dick.

_God._

Derek leans over, sliding his dick in the messy, spit-slick hollow of Stiles' ass, the head bumping and catching over Stiles' rim, making him shiver all over. "Eighteen," he whispers, biting down on Stiles' shoulder, sharp and piercing.

"Jesus, Derek," Cora says, her voice caught between husky and breathless. "Could you _be_ more of a dork? Though, honestly, the two of you are a matched set," she adds, petting through Stiles' hair until he's trying to coordinate leaning into the touches with rocking his hips back against Derek's. "This idiot's been writing his name."

Derek muffles a laugh into Stiles' skin, who just flushes, embarrassed.

"It's not like I have any experience at this," he grumbles, sending a longing glance down at the pink, glistening inner bits of Cora that are still spread open to him. He's pretty sure she's about to kick him out of bed for being a loser who reads Cosmo for oral sex tips.

But Cora surprises him by pressing his face back down, fingers of one hand tracing over the marks Derek's teeth left in his skin as she offers him direction. "Roll your tongue, keep the rhythm steady, then flutter the tip of it a little when you feel me getting close."

He takes her advice, concentrating on even, rolling sweeps of his tongue until his attention is fractured when Derek slides one long, thick finger into his ass. It goes in smooth and easy; he must have grabbed the lube while Stiles was otherwise engaged. Cora's bucking against his mouth when it happens and Stiles is so shocked his jaw opens wide, his teeth scraping over her clit. Cora _keens_ , her thighs clamping down on his shoulders. Stiles has just enough presence of mind to flutter his tongue and then she's damn near convulsing under him, upper body curving up as she holds his head still against her—like he has any plans to go anywhere—and then she's scrambling backward, curling up into a ball and shivering all over.

"Too sensitive when she comes the first time," Derek offers in explanation, crooking his finger until Stiles sees splotches of rainbow-colored stars at the peripheral of his vision. 

He knows what Derek is doing, he's even managed to tap that spot a couple of times himself, but he's never had this steady, even _massage_ and he's terribly afraid he's about to—

"It's okay, Stiles," Derek says, scratching over the tender skin of Stiles' ass with his free hand and just _pressing_ on his prostate with the finger in his ass and that's it. Stiles is fucking _gone_ , entire body spasming as he comes in long ropes across the bedspread and a even getting a bit on Cora's shin. 

Stiles falls forward, landing in the wet spot and sort of draping his noodley arms over Cora's thighs and smushing his face against the inside on her knee. He squirms, moaning softly when Derek wriggles the finger _still knuckle-deep in his ass_. "Wha?" he mumbles, tongue sort of glued to the roof of his mouth and aftershocks of pleasure zapping through his nerve endings every time Derek moves the tiniest bit.

"You didn't think we were through, did you?" Derek asks, voice gritty, reminding Stiles that while he and Cora are both happily blissful and floaty, Derek still hasn't come.

Stiles manages to lever himself up onto his elbows, freeing Cora to stretch and rearrange herself on the pillows while he twists around to get a good eyeful of Derek. A low whining sound shivers on the air when he sees Derek bent over him, one thickly muscled arm holding himself up while the other flexes with every motion of his finger inside Stiles.

Derek looks up at the sound, a wickedly dark grin tipping the corners of his mouth as he stares back at Stiles. And then he's easing his finger out, ignoring Stiles' bitten-off cry and chasing hips. When he kneels up, twisting around to reach for the lube, Stiles gets his first good look at Derek's fully erect dick and it is... Well, _Stiles'_ mouth is watering, that's for damn sure.

Deciding to do something about that, Stiles flops around until he's laying on his back, his head between Derek's spread knees. He curls his hands around the back of Derek's muscular thighs and just makes noises at him until Derek huffs out a laugh and leans forward, dragging the head of his dick across Stiles' lips. Which are still sticky from Cora.

Best. Birthday. Ever.

Stiles doesn't let Derek get away with that kind of teasing; instead, he parts his lips and swipes his tongue over the head of Derek's dick on the next pass, which has Derek hissing. A half-aborted thrust of Derek's hips pushes the tip of his dick into Stiles' mouth, and Stiles just goes with it. Opening his jaw wide and being careful with his teeth, he licks and sucks at Derek's dick as it slides in and out of his mouth. He thinks he's doing pretty good—much better than what he did with Cora, anyway—when his brain goes offline because suddenly _Derek's_ mouth is on _his_ dick, and honestly. He can't really be expected to concentrate on anything else when his dick is in Derek Hale's mouth, can he?

He's sensitive, maybe _too_ sensitive after coming his brains out, but his dick makes a valiant effort to get with the program. It's half-hard and getting harder with every flicker of Derek's tongue over his slit, but Derek is apparently impatient with Stiles' slack-jawed, lackluster blow job skills, because he kind of grinds his hips against Stiles' face. Someone pinches the back of his thigh—he actually thinks it's Cora—so he drags his attention off his own dick and puts it back on Derek's, where it belongs.

It's kinda funny, actually, how _different_ Cora and Derek taste. He couldn't even accurately describe it; for some reason his mind wants to whisper about light desserts and fine wine versus steak and craft beer.

Maybe he's just hungry. 

But Derek is thick and hard in his mouth, splitting his lips wide, and there's something thrillingly satisfying about that. Like maybe Stiles' mouth has finally found its purpose. He sucks a little harder in appreciation and is rewarded with a gasp and the stuttering of Derek's hips against his face.

There's pressure against the back of his thighs and Derek pulls off his dick for a second—Stiles would bitch about that, but his mouth is otherwise occupied—until they have Stiles' legs spread wide and pulled back. Yeah, _they_ because Cora's hands are definitely in the mix now. Derek curls his fingers around Stiles' ankles, effectively preventing him from moving his legs, then puts his mouth back on Stiles.

Yay. Seriously.

After a few more seconds of very mutual, very satisfying blow jobs, Derek lifts his hips, slowly pulling his dick out of Stiles' mouth. It's a relief and a disappointment all at once—his jaw is definitely feeling a bit overused—and Stiles lifts his head, chasing after Derek and lipping at his head until it's finally beyond reach.

He opens his mouth to ask questions only to make a gurgling noise when Cora spears two fingers into his ass. He knows it's Cora because Derek's hands are still securing his ankles. Derek gives an extra hard suck and a roll of his tongue over Stiles' dick just as Cora presses hard against his prostate. He doesn't come, but he's not entirely sure how he managed not to. 

Turning his head, Stiles muffles the embarrassing noises he's making against Derek's thigh. Then he bites it, just to feel Derek's body give a shivery shudder. Almost like retaliation, the fingers in his ass twist and pull, opening him up. He bites harder, startled.

"Stiles," Derek growls warningly, pulling off just to say that. 

Glaring down between their bodies at the underside of Derek's chin, Stiles finally remembers he has hands—don't judge; kind of a lot has happened to him in a very short period of time—and spits on one before wrapping it around Derek's dick, where it's swaying temptingly just beyond reach of his mouth. Unfortunately, Derek immediately pulls off him with a muttered curse. When he doesn't immediately get back on task, Stiles looks down again, only to let out a low moan when he sees that Cora and Derek are sharing a sloppy, open-mouthed kiss over his dick, while her fingers are still corkscrewing inside Stiles' ass. Getting him nice and slick and open for... Stiles' fingers spasm around Derek's dick, forcing a high whining sound from him. 

"Gonna..." he hears Derek say, then Cora lets out a low laugh that rolls through Stiles, lighting him up.

"Not yet," she says, her voice firm and commanding enough to send a thrill of _something_ through Stiles. His legs fall open further for her just on the power of her voice. "There's no way he's ready for your knot."

Stiles goes perfectly still, his voice cracking when he asks, "Sorry, what did you say?"

Reaching down and dislodging Stiles' hand from his dick, Derek turns around and repositions himself so he's leaning over Stiles, his lips red and shiny from where he'd been sucking Stiles' dick. Or maybe from kissing Cora. Oh fuck, Stiles is completely ruined for sex after this, isn't he?

While Cora continues to finger-fuck Stiles' ass, Derek grins down at Stiles—which kinda makes his brain go offline because holy shit, Derek should smile more often, _damn_ —and says, "So, remember when you asked me if knotting is a thing?" Bending down, he sucks Stiles' bottom lip into his mouth and nips at it before letting it go and whispering into his mouth, "The answer is yes. I'm going to knot you, Stiles." He slides his mouth across Stiles' cheek to his ear and begins whispering filthily, "I'm going to slide my dick into your ass. When you're begging me for more, I'll pound into you until I come. My dick is going to fill you up until you think you can't take any more. Until you think you're going to tear apart. Until you're crying, but you're not sure if it's from the pain or the need for _more_." Biting at Stiles' ear, Derek murmurs, "Yes or no, Stiles?"

"God, _god_. Yes, please. Please, Derek!" Then, "Cora!" because Cora hasn't exactly been inattentive during Derek's little brain-melting speech—she's almost got her whole hand in his ass now, shoving it in past the bridge of her knuckles and only stopped by the splay of her thumb. She gently twists her hand, stretching him, stretching… His back arches and he can't stop a little sob from spilling from his throat. It's so much. So much everything, from Derek's warm body leaning over his, his mouth and breath on Stiles' ear and throat, to Cora's hair brushing silkily against his thigh and groin and her hand in his ass.

That really can't be emphasized enough. Capitalize it, bold it, and put it in thirty point font because, damn, her _hand_ is in his ass. Preparing it for _Derek's knot_.

A laugh surprises him, especially because it's coming from him.

"What?" Derek asks, and Stiles can feel the curl of _his_ lips. Like just the sound of Stiles' amusement amuses him.

"I don't… hnngh," he groans, distracted when Cora curls her fingers inside of him, "I don't think I can explain it."

"Cora," Derek says, licking at Stiles' throat. "Hurry up. I think we're losing him."

"Oh, were you waiting on me?" Her voice is all sweetness, which sends a bolt of unease through Stiles because Cora is not _sweet_. "I've been done for ages. But Derek, you're going to love it down here. He's so tight and smooth and _hot_." Stiles chokes on a gasp when she strokes her fingers against the walls of his ass.

Derek groans and drops his head to Stiles' shoulder, growling when Cora's mocking laughter rolls through the room.

A shock of pain jolts through Stiles when Cora pinches the thin skin of his stretched rim between her thumb and the bridge of her hand. "Aaahhhh. Wh-whhu?"

"My turn, you lazy bastards."

Derek snorts, but slowly crawls backward until he's completely off Stiles, allowing Cora, who removes her hand from Stiles' ass—he thinks he might actually cry he feels so empty—to crawl up the bed until she's kneeling over Stiles' face. 

"Just a little bit," she says, winking down at him. "Don't want to come again until you're in me."

"Jesus Christ," Stiles whispers, looking up at her, his eyes damn near rolling in their sockets. "You do know I'm not going to last at all, right? I mean. This is too much."

"Oh, don't worry about that," she says, reaching down and parting her outer labia, sliding her fingers over herself slowly until he can see her glistening anew. "You'll last long enough. Trust me." She lowers herself to his mouth before he can question that, and he just narrows his eyes and nips at her gently in retaliation. 

Almost at the same time that he's finding his rhythm again—it's easier this time, he knows what he's looking for—Derek slides three slick fingers into his stretched ass. He doesn't go looking for Stiles' prostate, just continues stretching and loosening Stiles' ass. Cora had done a good job getting him there, but Derek's hand is wider, his movements more efficient. By the time Cora is jerking against him and pulling away, her eyes glassy and entire upper body flushed red with arousal, Stiles feels like his ass is literally gaping open.

Cora scrambles backward on the bed, then flips over onto her hands and knees and stretches, cat-like, her upper body curving down toward the mattress, her hands reaching toward the headboard, and her ass just thrust into the air, her cunt wet and swollen-looking. "Now, now, _now_ ," she growls, rolling her head to glare at Derek, who removes his fingers from Stiles' ass with a smirk and a light smack. 

"You heard her," Derek says, and then manhandles Stiles until he's kneeling over Cora. Derek's hand on his dick guides him to the hot, damp entrance of Cora's body, his fingers lingering to stroke over and around where the head of Stiles' dick parts her folds.

Stiles bites his lip, his head dropping back when Cora gets impatient and rocks backward, engulfing him in clenching, wet heat. He doesn't remember grabbing her hips, but now his fingers hurt from how hard he's gripping her. He tries to loosen his hold, but Cora just growls at him, so he goes with it. Keeps his fingers tight and uses that hold to rock her body forward and backward, meeting the thrusting slaps of his hips. He looks down at where her body is swallowing him up and he knows he's about two seconds from going off like a cork. He can feel his balls tightening, drawing up against his skin, and he starts to lose his rhythm, his hips jerking spasmodically as his stomach starts to clench.

But then Derek growls Cora's name and something happens. He has no idea what it is, to be honest. But Cora shoves backward when Derek pushes him from behind—and he hasn't missed the fact that Derek _still_ hasn't put his dick in Stiles' ass, what the fuck—trapping him between them. Cora's body clenches down on his dick, right at the very entrance of her body, and keeps clenching, swelling more and more from the inside until his choices are to stay still or let her body rip his dick off. It freezes his orgasm right at the cusp, and he's left hovering there while the rest of her passage _milks_ the length of his dick, dragging sounds from him that he's not entirely sure are human.

And that's when Derek pushes him down, making him curve over Cora's back, and slides his dick into Stiles. It should be smooth and easy, but there's still a burning stretch and Stiles is just blubbering now, caught between them, while Derek starts pumping his hips, his dick glancing wildly over Stiles' prostate, and Cora body continues milking his cock.

He's going to die. There's no way he's going to be able to survive this kind of pleasure.

He tries to prolong his life by focusing on the slapping of Derek's hips against his ass—the skin is still tingly and sore from all the spanking earlier—but that just makes him hypersensitive to the feel of Derek's man-scaped pubes scratching over his sensitive skin, the stretch and tug of his rim as Derek pistons in and out, the lightning flashes of pure pleasure when his dick rubs just right.

And then _Derek_ starts to lose his rhythm, hitching against Stiles' ass in stuttering, jerking motions, and his dick is swelling. It's swelling, and stretching Stiles wider, pulling his rim thinner. He's caught between Cora's vice-like grip and Derek's impossibly wide dick and Stiles… well, he screams.

It's not a bad scream; he's pretty sure they know what his _holy shit there's an acid-spewing sludge monster eating the town_ scream sounds like, and this isn't that. This is just his only remaining response to the overwhelming feelings bombarding him. Pain and pleasure and ecstasy as he just splays over Cora's back, his whole body shaking like a goddamn leaf.

Derek does something then, and they all end up on their sides without catastrophe—namely, Stiles' dick being ripped off by Cora's super-cunt, thank god. Derek's arm stretches around Stiles and catches Cora by the hip, using her as leverage so that he can push himself harder against Stiles, forcing his dick in that last tiny bit. And then he goes perfectly still as his dick just… expands. More and more.

It should be impossible. It should be impossible that Derek's dick is capable of swelling any more than it already has, but the proof is in Stiles' ass. By the time it stops—or at least, Stiles thinks it has—he's reduced to nonsense sounds and blurting phrases. 

He still hasn't come, even though he's been riding on the edge of his orgasm for long enough that it feels like electricity under his skin. He's not sure what's going to happen here, how long this is going to last, but he's pretty fucking positive he's going to black out and miss the best orgasm of his life, and that? That's really fucking sad. 

Derek laughs against the back of his neck, which jolts his body and, in turn, his knot inside Stiles' ass. Stiles just writhes, not even able to summon enough strength for a breath. He's choking on Derek's dick, on Cora's cunt, on the warmth and strength of the bodies caging him in. He can't do anything but jerk like a fish on the world's most amazing hook. Derek smoothes a hand over his chest, murmurs his name in his ear, and suddenly Stiles is gasping, dragging air into his lungs, just enough to sob at the overpowering sensations he's trapped inside. 

When he's recovered as much as he's going to, Derek's hand slides from his chest down his arm and he threads their fingers together, his palm lined up with the back of Stiles' hand. He lifts them and wraps them around Cora again, but reaches lower, between her legs. He directs their joined fingers to the juncture of her thighs and slides them through the slick heat. Stiles' finger glances over her clit and a low-pitched sound begins to fill the room.

 _Cora_ starts writhing then, and it's all wrenching, painful pleasure for Stiles, who is still caught inside her, attached at the dick, so to speak. With every roll of her body, she forces Stiles to move, which makes him tug on Derek's dick in _his_ ass. It's a chain of events that only has one conclusion, but that conclusion is impossible until Cora's inner muscles let up on him enough to allow him to come.

With Stiles on task, lightly pinching and rubbing at Cora's clit, Derek releases his hand and skims his own fingers up over Cora's belly to trace lightly over her nipple. With their combined efforts, Cora is soon growling through her own orgasm. The clamp of her muscles on Stiles eases just enough to allow the orgasm that's been building and building— _and building_ —to overtake him.

His vision goes snowy like an ancient television with poor reception and heat races through his body, just under his skin, flames of pleasure that lick through him and converge in his balls before rolling up his dick. He's never felt anything like this before and he's not even entirely certain he ever wants to again—it's too good, too much, too fucking overwhelming to put into words. His dick pulses an unprecedented number of times; it's as close to multiple orgasms as he's ever come, but it's just one long, rolling wave of pleasure. As he comes, his entire body clenches up, including his ass, which apparently triggers Derek's orgasm. 

They're caught like that, rocking against and between each other, all of them making noises that they'll later laugh at each other over. Stiles is a mess, his own come being rubbed into his groin with every roll of Cora's hips against him as she continues to ride out her orgasm. Now that he's no longer locked up tight in her body, all he wants to do is stay in it, but his balls are drained dry and his dick is softening with every second. When he finally slips out of her, they both make choked-off noises of distress, and without thinking, he shoves three fingers inside her, instinctively trying to keep her full of him.

Derek's still buried in his ass, still coming, still grinding his hips against Stiles with his knot still inflated. It's tugging against Stiles' rim with every heartbeat, but he's beyond feeling things like pain now. His body is completely limp, he has no ability to do more than lay there and breathe while Derek uses him as he will.

"Let me," Derek whines, his voice right in Stiles' ear, begging him for something. But since Derek's already coming, Stiles honestly can't figure out what more he wants. 

Sucking in a breath, Stiles tries to fire up his brain enough to think, and realizes it's pointless. His brain melted out his ears hours earlier, right after they got back to Derek and Cora's apartment and the Hales surrounded him, blocking him between their bodies and offering him the first kiss of this whole, wildly unexpected encounter. With everything else they've done here, though, it's not like there are any lines left to be crossed, so Stiles just nods and hopes Derek understands that to be the permission he was searching for.

Apparently he does because no sooner has Stiles' chin dipped than Derek's teeth are sinking into the back of his neck, holding him perfectly clamped between Derek's jaws as he pulls Stiles tight against him and _continues_ coming. Stiles lets out a hysterical-sounding laugh and _he's_ not even sure what he's laughing at. Is it the fact that a _werewolf_ has his teeth locked in Stiles' neck? Is it that he's got what feels like an entire liter of come in his ass with more pumping in by the second? Is it the whole fucking _night_?

He'd like to point out, for the record, that he'd been a virgin when he got in the car this afternoon. Now, not only has he had sex with multiple people, they were siblings, and werewolves, and apparently all those documentaries about how wolves mate had been really fucking accurate… to a point. None of them had shown female wolves doing whatever it was Cora had done. Reverse knotting? No idea. He'll ask them later. Maybe.

But he's also laughing because he's not exactly trying to get away. Hasn't tried at all, actually, and doesn't really _want_ to except for how he thinks he should. In fact, he's kind of leaning into the press of Derek's teeth, wanting more of it, more of the throbbing, burning, sting of teeth sinking into his flesh. Wants Derek to split him open. Wants Cora to turn around and add her teeth to the mix. Mark him up on the outside as much as they did on the inside, because he's never coming back from this. Nothing else, no one else, will ever measure up to this moment.

So he wants their teeth in him and his teeth in them and… and he wants never to let go. Just stay here, now.

While he's having his existential crisis, Cora sighs and snuggles up close to him, trapping him once more between herself and Derek. Not that he wants to be anywhere else. She grabs his hand, wraps his arm around her, and grunts, "Cuddle me, asshole."

With Derek's teeth in his neck and dick in his ass, Stiles just gives up on thinking, tightens his arm around Cora and does as commanded. He cuddles the fuck out of her.

**Author's Note:**

> Aaaand, this is the part where I put my [tumblr info](http://eeyore9990.tumblr.com) and encourage you to follow [me](http://eeyore9990.tumblr.com), but that'd be terribly [self-promotional](http://eeyore9990.tumblr.com), don't you think? *drinks wine from a wine glass and not a red solo cup*
> 
>  
> 
> Also, for those who see this and are waiting on that, I'll be updating the Frail Humanity series by this time tomorrow with the smutty epilogue/sequel thing.


End file.
